Atom-by-atom simulations of graphene growth by decomposition of SiC (0001): Impact of the substrate steps

The atomic-scale carbon rearrangement into graphene by the thermal decomposition of SiC (0001) was simulated by the density-functional tight-binding technique. By decomposing the terrace of the SiC (0001) surface, the carbon chains formed a three-dimensional structure, because the carbon atoms are released by losing their original contacts to silicon atom. On the other hand, in the step model, the silicon atoms at the step-edge act as trapping sites for the released carbon atoms, and the carbon network effectively nucleated and expanded. After nucleation at the step, graphene can grow by the further decomposition together with retreat of the step.